There are a number of methods used to mount modern semiconductor devices.
A flip chip is an integrated circuit (or other semiconductor device) that is connected to other circuitry, such as a circuit board or another integrated circuit, through solder bumps, balls, or other protrusions deposited onto pads of the integrated circuit. The solder is generally deposited on the top side of the integrated circuit during processing, and the integrated circuit is then flipped over to align the pads of the integrated circuit to pads on the other circuitry to which the integrated circuit will be connected. Next, the solder is often re-melted to bond the integrated circuit to the other circuitry.
A ball grid array (BGA) is a type of device packaging that is used to surface mount semiconductor devices to, for example, printed circuit boards. In a BGA package, one face of the semiconductor device has pads in a grid pattern, and each pad includes a solder ball or other protrusion. To join the semiconductor device to the printed circuit board, the pads of the semiconductor device are aligned with corresponding pads on the printed circuit board, and the solder is melted, cooled, and solidified to permanently join the components.
A multilayer circuit board generally has a number of different layers or planes, the individual layers functioning as signal layers, ground layers, power layers, or mixed use as examples. The different layers may be connected by vias, allowing a signal to be transmitted through the layers, in a direction that is generally perpendicular to the layers.
High frequency signals are generally propagated from a signal source to a load using conductors in a coaxial arrangement where the center conductor is generally considered to carry the signal current. Signal current must return to the signal source and the outer conductor of the coaxial structure provides a tightly coupled return path. The outer conductor is usually at ground potential and is commonly referred to as “ground.” Tightly coupling the return current path to the signal helps prevent signal transmission or radiation to undesired locations thus “shielding” the signal from external objects. Other arrangements are used. For example, a common structure known as “twinax” uses two signal conductors and surrounds the signal conductors with a conductive “shield” and is generally used for differential signals. In still other arrangements, more than two signal conductors are used. Another variation is when the signal return is at a potential other than the circuit ground reference voltage
Embodiments of the disclosed technology address shortcomings in the prior art.